• Eric Dumazet's avatar
    net_sched: gen_estimator: complete rewrite of rate estimators · 1c0d32fd
    Eric Dumazet authored
    1) Old code was hard to maintain, due to complex lock chains.
       (We probably will be able to remove some kfree_rcu() in callers)
    
    2) Using a single timer to update all estimators does not scale.
    
    3) Code was buggy on 32bit kernel (WRITE_ONCE() on 64bit quantity
       is not supposed to work well)
    
    In this rewrite :
    
    - I removed the RB tree that had to be scanned in
      gen_estimator_active(). qdisc dumps should be much faster.
    
    - Each estimator has its own timer.
    
    - Estimations are maintained in net_rate_estimator structure,
      instead of dirtying the qdisc. Minor, but part of the simplification.
    
    - Reading the estimator uses RCU and a seqcount to provide proper
      support for 32bit kernels.
    
    - We reduce memory need when estimators are not used, since
      we store a pointer, instead of the bytes/packets counters.
    
    - xt_rateest_mt() no longer has to grab a spinlock.
      (In the future, xt_rateest_tg() could be switched to per cpu counters)
    Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    1c0d32fd
act_api.h 5.96 KB